US20100161102A1 - Method of providing an identifiable powder amount and method of manufacturing an object - Google Patents

Abstract

In a method of providing a material amount for a generative manufacturing method, a three-dimensional object (2) is formed by selectively solidifying layers of a material at locations corresponding to the cross-section of the object (2) in the respective layers. It is the object of the present invention to provide a method, by which the quality of the manufactured objects is reproducibly recorded and, thus, further improved. Therefore, the method is characterized by the steps of:

• • providing at least one first material amount, which is characterized by at least one feature; detecting data, which relate to the at least one feature of the first material amount; and storing data, which relate to the at least one feature of the first material amount.

Description

• The present invention relates to a method of providing a powder amount, in particular for laser sintering, and to a method of manufacturing a three-dimensional object, in particular by laser sintering.
• In the field of layerwise building methods, in particular in laser sintering, the quality of the generated object depends on the quality and the characteristics of the used powder. The characteristics of the used powder are often not sufficiently known, since the composition of the powder is often not known by admixture of powder, so-called waste powder, which has already been used in previous manufacturing processes.
• For determination of the powder characteristics, for example the so-called melt volume rate method (MVR) is used, where a molten mass of powder is generated and the viscosity of the molten mass of the powder is determined, which can give information about the age of the powder. Further, the melting point can be determined. However, this method is time-consuming and not applicable in all cases.
• From DE 10 2006 023 484, devices and methods are known, by which the quality of objects to be manufactured by laser sintering can be improved, wherein a mix of fresh powder and waste powder is used.
• It is the object of the present invention to provide a method of providing a clearly identifiable powder amount for layerwise building methods and a method of manufacturing a three-dimensional object, by which the quality of the manufactured objects is traceable recorded and thus further improved.
• This object is achieved by a method according toclaim1 and by a method according toclaim12. Further developments of the invention are defined in the respective dependent claims.
• It is an advantage of the inventive methods that it is known at any time which powder components have been used for a manufactured object. For example, the percentages of fresh powder and waste powder as well as the built total powder amount are known, and all data can be centrally managed by the IQMS (Integrated Quality Management System). The used powder and the objects built therefrom can be traced in a manner of a flow sheet up to the manufacturing.
• The composition of each individual layer can be determined. The quality of the manufactured object is thus verifiable. By the quality control of the manufactured objects, which is performed in that manner, a corresponding certification (QMS) can be issued. Further, it is possible to relate the building parameters of the laser sintering machine to the characteristics of the used powder. Further, the laser sintering machine can be calibrated in accordance to the used powder.
• It is a further advantage that reproducibility of the manufactured objects is ensured, since all parameters necessary therefore are known. This is required by many producing companies such as in aircraft industry, since very strict regulations have to be taken into account due to safety reasons.
• It is a further advantage that maintenance staff and customers get insight with respect to reliability and workload of the machines by the recorded data. The conditions of the machine, the parameters thereof and irregularities and errors, respectively, are traceable, which may occur during a layerwise building method. Occurring problems can be quickly and economically solved by this manner.
• Further features and objects of the invention can be gathered from the description of embodiments on the basis of the attached figures. From the figures show:
• FIG. 1 a schematic view of a laser sintering device,
• FIG. 2 a schematic view of a system for providing a powder amount according to the invention,
• FIG. 3 a schematic view of a method according to the invention having the method steps of “cooling”, “unpacking”, “collecting”, “mixing”, “manufacturing”,
• FIG. 4 an example of a material flow diagram.
• In the following, a first embodiment as an example of laser sintering is described with respect to the figures.
• Thelaser sintering device1, as exemplary depicted inFIG. 1, has abuilding container100, which opens to the top and has asupport200 being vertically movable therein, which supports theobject2 to be formed and defines a building field. Thesupport200 is set in the vertical direction such that the respective layer of theobject2 to be solidified lies within aworking plane400. Further, anapplicator500 for applyingpowder3 is provided, which can be solidified by electro-magnetical radiation. Thepowder3 is supplied in a predetermined amount from astorage container24 to theapplicator500 by ametering device600. Further, alaser700 is provided and generates alaser beam700a, which is deflected by deflecting means800 to anentrance window900 and passed therefrom into theprocess chamber1000 and focused to a predetermined point within theworking plane400. Further, acontrol unit110 is provided, by which the components of the device can be controlled in coordinated manner to perform the building process.
• For manufacturing theobject2, thepowder3 is applied by theapplicator500 in layers onto theworking plane400. Thelaser beam700aselectively solidifies thepowder3 at locations corresponding to the cross-section of theobject2 in the respective layers. Thereafter, themovable support200 is lowered, and the next layer ofpowder3 is applied by theapplicator500 onto theworking plane400. The steps are repeated as often as possible until theobject2 is finished. Thepowder3 can be a synthetic powder, a metallic powder, coated sand, ceramic powder, mixtures thereof or also a pasty powder composition of any powder.
• Thepowder3 which has already passed through one or several building processes, but has not yet solidified, is calledwaste powder4 and has material characteristics altered by this process and by the heat entry involved therewith.
• The method according to the invention detects at each building action, in which theobject2 is manufactured, the powder composition and therefore also the characteristics which can be gathered from this information. This information about the powder composition and the characteristics of the powder mixture are taken into account at the next building action for calibrating the building parameters and for possible certification (Quality Management System-QMS) of the work pieces.
• FIG. 2 shows a schematic view of the system for providing a material amount and a powder amount, respectively, for performing the method according to the invention. All process data are managed in a centralpowder data base6. The centralpowder data base6 exchanges information with thelaser sintering device1 as well as with a watch dog and atime server7, respectively. Thetime server7 manages the chronological sequence of the manufacturing processes. This is important when more than onelaser sintering devices1 are used, for instance. Thetime server7 in turn exchanges information with a powdertracking data base8.
• The powdertracking data base8 records and monitors the usedpowder3, that means, the usedwaste powder4 as well asfresh powder5 which is supplied to the system and has not yet passed any manufacturing process. In this manner, it is secured that it can be exactly determined, which powder composition is present in thegenerated objects2. The powdertracking data base8 is connected to the centralpowder data base6 as well as to aterminal11 which is either operated by auser12 or controlled via software. Theterminal11 monitors the use ofwaste powder4 as well asfresh powder5. In theterminal11, the data provided by thepowder data base6 cannot automatically entered by theuser12, such as the powder amounts and the characteristics thereof, which are discharged from or supplied to the system. Dischargedpowder3, which is weighted by afirst weighing machine14, is provided with a label such as a RFID-chip, the label having a barcode or any other mark. In a similar manner,powder3 can be introduced into the system by a weighing machine.
• The individual amounts of the waste powder charges are built by thelaser sintering device1. Before that, thewaste powder4 can also be mixed withfresh powder5 in amixer17. By selecting the mixing ratio, the material characteristics such as tensile strength, modulus of elasticity, thermal conductivity, etc. of the later-finished work piece can already be defined at this early stage. A complex individual analysis for determining the characteristics is thus superfluous at this process step. By the known mixing ratio, it is further possible to optimally set the parameters of thelaser sintering device1 for example with respect to the melting point of the usedpowder3.
• Whenfresh powder5 is filled in themixer17, theuser12 and theRFID13, respectively, transmit the information about the amount, the charge, etc. to theterminal11, which transfers the information to the powdertracking data base8, which in turn forwards the information to thepowder data base6.
• Thefresh powder5 is weighted by asecond weighing machine15, before it is mixed with thewaste powder4. The used amounts of waste powder and fresh powder are centrally stored in thepowder data base6. The mixing ratio of waste powder and fresh powder is also stored therein. In this manner, the system knows at any time whichpowder3 is built where, when and in which composition. The generatedobject2 can be exactly determined with respect to its composition. For this purpose, a quality certificate (QMS) can be remitted by the manufacturer. The determination of the circulating powder amounts can be performed by the analysis of the generatedobjects2, the parameters of the used metering means for supplying thepowder3, the area factor of the respective building processes, the building height, the mixing ratio of thepowder3 and the weighted amount of thefresh powder5, for example.
• Via aninterface9 and an IQM (Integrated Quality Management System)information centre10, respectively, it is possible to check and maintain the system internally or externally. It is possible by means of the IQMS, to detect and record errors during the manufacturing process.Objects2 are subsequently controlled, in which irregularities and errors have been detected during the manufacturing process. In this manner, a high quality (for example surface quality) of the manufactured parts can be secured and recorded. Moreover, monitoring of the laser behavior, the laser operation and the temperature distribution can be realized. The collected data are used by the manufacturer for further optimizing the processes and for remitting quality certificates. Furthermore, the manufacturing processes and the thus generated work pieces are reproducible.
• Further, external components can be provided, which communicate with the system.
• FIG. 3 shows an example of a method having several method steps “cooling”, “unpacking”, “collecting”, “mixing”, “manufacturing” (laser sintering device1) of a first embodiment.
• First, thelaser sintering device1 manufactures oneobject2 orseveral objects2 at the same time in a building action (job). This information is entered into thejob data base18 and then called by thetime server7. Thetime server7 subsequently informs the powdertracking data base8. In the meantime, thepowder3 is replenished inpowder containers25 of thelaser sintering device1, which are provided therefore. In themixer17,fresh powder3 is generated by mixingwaste powder4 and/orfresh powder5. Thepowder data base6, which images the quantitative and qualitative powder track in the system, will be informed about how much of fresh powder is created, and the powdertracking data base8 gets the information about which ID has been allotted to the created powder.
• If thepowder container25 and/or the powder conveyance routes are empty, they are controlled by the powdertracking data base8 and replenished with supported by theuser12 and theRFID13, respectively.
• It is possible to form theobject2 and theseveral objects2, which are generated in one building action, bydifferent powders3. It is also possible to build each individual layer by adifferent powder3. As soon asfresh powder3 and a powder mixture different from the previously used powder mixture are supplied, respectively, it is recorded by the system, in which layer of theobject2 and theobjects2, respectively, that means in which building height, thepowder3 has been altered. By detection of the amount of the powder flow by the powder metering means in thelaser sintering device1, the system automatically recognizes, at which time a powder characteristic has been altered.
• As soon as the building action is finished, this information is transmitted to thejob data base18 and will consequently be red by thetime server7. Thetime server7 in turn informs the powdertracking data base8 so that the builtfresh powder5 can be passed for calculation now. For example, this calculation can be performed in that the manufacturer of theobjects2 buys a contingent of fresh powder from the powder manufacturer and gets therefor a certain number of powder units such as kg-units, which are then used during the several building processes. In this manner, it is secured that only powder is used, which is tuned to the respectivelaser sintering device1.
• By finishing the building process, new identification numbers (ID's) for thenon-built waste powder4 and the manufacturedobjects2 are generated. An ID is allocated to a specific powder amount, by which the handling sequence of the powder amount is reproducible. The powdertracking data base8 informs thepowder data base6 about the changed powder amounts in the system. Thepowder3 used for the generatedobject2 leaves the system as an output. The generatedobject2 is taken from the building container100 (seeFIG. 1) for cooling and transported in thecooling station30. As soon as theobject2 is cooled-off, it is further conveyed to the unpackingstation31. During unpacking, respective ID's for eachobject2 and eachwaste powder4 result from the several generated ID's.
• Acollector32 is provided, which comprises two wastepowder collecting containers33. As soon as one of the wastepowder collecting containers33 is full, this one will be stirred. In order to achieve a constant mixture, thewaste powder4 is transported to the other wastepowder collecting container33 and collected there. Thus, themixer17 is only supplied with the analyzedwaste powder4. For example, it is also conceivable to store aspecific powder3 in order to build the same on demand. This secures the possibility of exact reproduction of specific work pieces andobjects2, respectively.
• Since a plurality of mixtures can result after several manufacturing processes (jobs), it is advantageous to collect thewaste powder4 of several jobs, to mix them up thereafter, and to mix them again with fresh powder only thereafter. It is an advantage that the mixtures are kept comparable in this manner in order to secure a stable powder quality.
• It is also conceivable to perform the method withoutcollector32.
• Subsequently, thewaste powder4 is conveyed in themixer17 and, if applicable, mixed withfresh powder5 there.
• FIG. 4 shows an example of a material flow diagram including nine steps, which are described in the following.
• The process is started by providing a charge of fresh powder. A part of thefresh powder5 of this charge is used for one building action or for several building actions in one or severallaser sintering machines1. Thefresh powder5 is labeled by an identification number (ID) before, and it is quantitatively (indication of kg) managed in the system. Thewaste powder4, which has not been solidified during the building action and the building actions, respectively, is used again in a later building action. The manufacturing duration is also detected by the system. The waste powders4 of several building actions are mixed up to a new powder mixture. This new powder mixture gets a new ID, which is also detected by the system. The proportions of the composition of the powder mixture is known by the system.
• In the further process steps, the generated mixtures of waste powders can be added with furtherfresh powder5. This information is also detected by the system, for example by entering the amount of fresh powder in the terminal11 (seeFIG. 2). Each new powder mixture gets an own ID.
• The difference in amount of thepowder3, for example fromstep1 to2 (100 kg input-75 kg output), is made up by the builtpowder3, that means theobject2, and the loss powder due to cleaning and recovering actions, respectively.
• Instep9, for example the powder ID11 (46 kg), ID12 (24 kg) and ID13 (17 kg) from the machines are mixed. At this time, 87kg powder3 havingID14 are obtained. Thispowder3ID14 has portions of thecharge234 and thecharge302. The portion of thecharge234 has already passed three manufacturing processes, and the portion of thecharge302 has already passed two manufacturing processes and one manufacturing process, respectively. That means, a waste powder portion “of the first order” of the charge302 (singular use) as well as a waste powder portion “of the second order” of the charge302 (double use) are in thepowder3ID14.
• The manufacturing process can arbitrarily be continued in this manner. In addition to the describedlaser sintering devices1, furtherlaser sintering devices1 can be added, for example.
• As minimum information for the material flow, an identification (for example an identification number) and the weight of the relevant powder amounts are required. Additional information such as a time stamp, that means a time of manufacturing and mixing, respectively, the machine number, the job information, the stay time of thepowder3 in the machine, the charge and information such as the present temperatures, material data, etc. can be supplemented, if applicable. By these material flow diagrams, the material composition and the alteration can be traced from each step. For example, the material ofjob5 in the machine SI777 can be traced up to the first mixture. Thereby, it is possible to determine the powder composition of manufactured objects2. Specific forms of the material flow by use of time stamps also enable one or several changes of the powder ID during a job in alaser sintering machine1.
• Further, the method according to the invention is not restricted to the use in a laser sintering machine. Rather, the method is applicable to any layerwise building methods, in particular to methods which use powder materials.

Claims (27)

1-21. (canceled)

22. A method of providing a material amount for a generative manufacturing method in which a three-dimensional object is formed by selectively solidifying layers of the material at locations corresponding to the cross-section of the object in the respective layers, the method comprising:

providing at least one first material amount, which is characterized by at least one first material feature,

detecting data, which relate to the at least one feature of the first material amount, and

storing data, which relate to the at least one first material feature.

23. The method according toclaim 22, further providing the material amount with an identification number (ID), by which a handling sequence of the material amount is reproducible.

24. The method according toclaim 23, further identifying the first material feature by the identification number (ID) of the material amount.

25. The method according toclaim 22, further comprising the steps of:

providing at least one second material amount, which contains at least a part of the first material amount and is characterized by at least one second material feature, and

storing data, which relate to the at least one second material feature.

26. The method according toclaim 22, wherein the first material feature is a feature selected from the kind of the material, or the composition of the material, or the age or the amount of the material.

27. The method according toclaim 25, wherein the second material feature is a feature selected from the kind of the material, or the composition of the material, or the age or the amount of the material.

28. The method according toclaim 22, further comprising providing of a further material amount and storing the data of the further material amount.

29. The method according toclaim 22, further comprising storing the data in an electronic data base.

30. The method according toclaim 22, wherein the first material amount is fresh material, which has not been subjected to a manufacturing process, and further providing a waste material, which has been subjected at least one manufacturing process and has not been solidified therein.

31. Method according toclaim 30, further characterizing the waste material by a RFID-chip.

32. The method according toclaim 25, wherein the first material amount is fresh material, which has not been subjected to a manufacturing process, and the second material amount is waste material, which has been subjected at least one manufacturing process and has not been solidified therein.

33. Method according toclaim 32, further characterizing the waste material by a RFID-chip.

34. The method according toclaim 22, further comprising mixing the first material amount with a second material amount.

35. The method according toclaim 25, further comprising mixing the first material amount with the second material amount.

36. The method according toclaim 32, wherein the first material amount is a powder, the waste material is a waste powder, and the fresh material is a fresh powder.

37. A method of manufacturing a three-dimensional object in which an object is formed by selectively solidifying layers of a material at locations corresponding to the cross-section of the object in the respective layers, the method comprising providing a material amount according toclaim 22.

38. The method according toclaim 37, further comprising a step of selective laser sintering.

39. The method according toclaim 37, further comprising using a mixture of waste powder and fresh powder.

40. The method according toclaim 37, wherein the method of providing a powder amount is used for at least one layer.

41. The method according toclaim 37, further comprising recording the powder flow is recorded and/or controlling the powder flow by a feedback control during manufacturing of one or several objects.

42. The method according toclaim 41, further comprising recording an input and an output, wherein the input is formed by supplied powder and the output is formed by the generated object and waste powder, and/or feedback-controlling the input and output.

43. The method according toclaim 41, further comprising managing a plurality of actions for building objects at the same time.

44. The method according toclaim 43, further comprising managing the plurality of building actions in a chronologically synchronized manner.

45. The method according toclaim 22, wherein the first material amount is a powder selected from a polymer powder, and/or a metal powder, and/or a ceramic powder.

46. The method according toclaim 37, wherein the first material amount is a powder selected from a polymer powder, and/or a metal powder, and/or a ceramic powder.

47. The method according toclaim 24, further comprising allocating the identification number(s) of the material amount(s) and the feature(s) of the material amount(s) to the object that is formed.

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